Segmented Cathodic Protection Probe for IR Drop Elimination
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Solution Overview
Problem
Current cathodic protection monitoring systems face measurement errors due to IR drops in soil or water resistance, and they often require interrupting the current supply to avoid these errors, which can disrupt the protection process.
Innovation Solution
A segmented probe system with a galvanically corroding connection that isolates segments when the medium is corrosive, allowing for accurate polarization measurement without IR errors and without interrupting the cathodic protection current, using a multi-meter and power supply to assess cathodic protection levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current is impressed onto the protected metallic object to provide cathodic protection, then corrosion mitigation is achieved, but measurement error due to IR drop increases
Solution Approach 1:
The probe is divided into multiple segments (first segment, second segment, third segment) where the second segment acts as an insulator to electrically isolate the first and third segments. This allows the system to measure polarization between segments while current flows through the protected object, eliminating IR error without interrupting cathodic protection.
Solution Approach 2:
The second segment serves as an intermediary insulating element between the first and third segments. This intermediary component enables electrical isolation while allowing the probe to remain deployed in the medium, facilitating accurate polarization measurement without requiring current interruption.
2Measurement precision
If current supply is interrupted to avoid IR error in measurement, then measurement precision improves, but cathodic protection continuity is disrupted
Solution Approach 1:
By segmenting the probe into electrically isolated portions, the system can measure polarization continuously without interrupting the cathodic protection current. The first and third segments can be selectively connected to the protected object while the second segment maintains electrical isolation, allowing continuous measurement during ongoing protection.
Solution Approach 2:
The segmented probe design enables continuous cathodic protection to be maintained while allowing continuous polarization measurement. The insulating second segment prevents current flow through the measurement path, eliminating IR error without requiring interruption of the external power supply to the protected object.
3Measurement precision
If segmented probe with galvanically corroding connection is used, then accurate polarization measurement without IR error is achieved, but device complexity increases
Solution Approach 1:
The probe is segmented into multiple portions with defined electrical relationships. The first and third segments can be selectively electrically connected to the protected object while the second segment provides isolation. This segmentation enables accurate measurement without requiring complex external measurement equipment or current interruption mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise measurement of polarization without IR errors and allows for continuous monitoring of cathodic protection levels, ensuring effective corrosion mitigation without disrupting the protection system.
Implementation Method 1
The resistance of the soil or water and protected metallic object introduce a measurement error (IR error) due to a corresponding voltage drop from the resistance
Implementation Method 2
the fourth segment is a galvanically corroding connection between the fifth and third segments. The galvanically corroding connection of the fourth segment can include a material with a galvanically noble value, so that when the probe is set in a galvanically non-corrosive medium the electrical communication between the fifth and third segment is maintained through the galvanically corroding connection; additionally when the probe is set in a galvanically corrosive medium the galvanically corroding connection galvanically corrodes and the fifth segment is electrically isolated from the third segment
Implementation Method 3
Cathodic protection involves placing an anodic material in the common electrolyte with a corroding metallic surface and providing an electrical connection between the anodic material and the corroding metal. The anodic material can be galvanically anodic, or forced to be anodic with the use of an external dc power supply. The surface that is more anodic experiences corrosion, and the surface that is less anodic (or more cathodic) does not corrode.
Data Source
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Figure 2B
AI summary
An apparatus and method for monitoring cathodic protection of a protected object 10, where the apparatus and method include a probe 34 with five segments in series. The cathodic protection is provided by a system 20 with a power supply that impresses current onto the protected object 10. An anode is included with the system 20 that is also connected to the power supply. The third and fifth segments are in electrical communication through a corroding connector; that over time galvanically corrodes to electrically isolate the third and fifth segments. The second segment, which is a permanent isolator, is set between the first and third segment 36s. The third segment 36 is selectively connected with the protected object 10, When the third segment 36 is selectively disconnected from the protected object 10; measuring the potential difference between the third segment 36 and the first segment 38 yields a value for object polarization that is void of IR drop error.